**4. Optimization Approach for PLES Considering the Vision of "Beautiful China"**

Forty years after China's reform and opening up, China's land space has basically formed a relatively stable pattern [14]. The corresponding zoning research work also has a relatively mature framework of support, which is constantly being enriched and improved upon. Since 1950, China's regionalization has entered a widescale developmental period. However, no in-depth theoretical or methodological support for the zoning work was provided at this stage. At the same time, due to the limitations of the objective conditions and basic data, most zoning plans were relatively simple. At the end of the 20th century, zoning entered an ongoing stage of comprehensive zoning research, during which, many zoning schemes in China were developed with profound historical backgrounds closely related to the levels and needs of national economic development in the same period. The study of regionalization accordingly changed from serving mainly agricultural production to considering both agricultural production and economic development, and then, serving sustainable development. However, due to some contents being quite different in regional division, there is also no institutionalized guarantee for the identification of natural regionalization, which leads to the fact that it is not really absorbed by the economic construction planning of local governments, resulting in the failure to combine natural regionalization with economic regionalization, which entails certain restrictions in supporting regional sustainable development [85].

Planning for the national main functional area should represent the strategic background of basic planning in the future. Indeed, as the core means of spatial optimization at present, territorial spatial planning is an important part of the future national planning system. Moreover, PLES embodies the Chinese people's vision for "future" development. This vision represents the final and most direct spatial carrier for the national strategy to penetrate into people's livelihoods, and the ultimate optimization goal of planning implementation [86]. However, under the current strategic background of ecological civilization construction, there are many problems in the layout of "main function zones", "territorial space planning", and PLES. "Beautiful China" was a major strategic goal proposed at the 18th National Congress of the CPC, and represents a spatial carrier for realizing sustainable development of the Chinese nation, and enabling the Chinese people to enjoy better lives. To achieve the vision of "beautiful China", the territorial and spatial patterns in the new era should be scientific and orderly, and remain in line with the processes of both modern and sustainable development. Based on analyzing the internal relationship between ecological civilization, beautiful China, and PLES, as well as the scientific connotations of PLES, the overall optimization system of PLES should be guided by the vision of building a beautiful China supported by the needs of national strategic applications, and centered on the human–Earth coupling system theory. By comprehensively considering the multi-dimensional coupling relationships between subsystems of the population, society, economy, resources, and the environment, as well as various elements within the system, a large, complex, dynamic, and open geographical system can be formed (Figure 1).

**Figure 1.** Framework system for the overall optimization of PLES.

The overall optimization system of PLES includes the resource subsystem, population subsystem, social subsystem, economic subsystem, and environmental subsystem. Among them, the resource subsystem includes land resources, water resources, and energy. As the main carrier of future spatial planning, land resources are the core of PLES optimization. From the perspective of function, land resources can be divided into PLES. PLES has the characteristics of differences in spatial scale, functional complexity, and dynamic scope. Under different spatial scales and time nodes, the same territorial space can feature different, or even overlapping, properties of PLES [86]. Living space mainly functions as living land, providing resource support for population subsystems, and guaranteeing living needs. Production space mainly functions as production land, providing resource input for the economic subsystem, and meeting regional production demands. Ecological space mainly functions as ecological land, which provides ecological environment security maintenance capabilities for the environmental subsystem. As a compound land with multiple functions, public resources provide services for the resource supply, management, substitution, and compensation of social subsystems. In the process of land resource utilization, the population, society, and economic subsystem are also accompanied by the utilization of water resources and energy. The utilization of water resources includes production water for the agricultural and service industries, domestic water for urban and rural areas, and ecological water. Energy utilization includes production space energy consumption, living-space energy consumption, and ecological-space energy consumption. In the resource subsystem, land resources, water resources, and energy are interrelated through different avenues that, together, constitute the resource basis for the utilization and development of PLES. The different utilization modes, industrial structures, and development degrees of PLES determine the intensity of regional carbon emissions caused by the different quantitative methods of mutual demand between water, soil, and energy elements [87]. Therefore, constraints such as boundaries, red lines, and standards of land

resources, water resources, energy, and carbon emissions should be taken into consideration in the overall optimization system for PLES.

Optimizing the quantitative structure and spatial layout of PLES based on water–land– energy–carbon constraints solves the problem of the pattern level of PLES. However, this optimization only reflects the application of the national strategy in territorial space optimization, and does not express people's demands for high standards of living, production, and ecological and environmental safety, which would involve solving the qualitative level of PLES. In the Evaluation Index System and Implementation Plan for the Construction of a Beautiful China issued by the National Development and Reform Commission on 28 February 2020 [88], 22 indicators in the five categories of fresh air, clean water, safe soil, good ecology, and clean living were used to evaluate the construction of a beautiful China. These indicators are a direct reflection of the production environment, ecological environment, and living environment in the overall optimization system of PLES. Therefore, the evaluation results for the construction of a beautiful China will directly test the qualities and benefits of the overall optimization of PLES in order to realize the overall optimization of PLES under the dual constraints of patterns and benefits.
